fix(#96): respect PORT env var for dev server (was hardcoded 3000) (#109)

The 'dev' and 'start:dev' scripts hardcoded --port 3000 on the CLI,
which collided with Baileys/WhatsApp bridges and other services that
also default to 3000. Users couldn't relocate the workspace without
editing package.json.

Changes:
- Drop --port from the CLI scripts; vite.config.ts now owns the port
- vite.config.ts reads process.env.PORT (default 3000) so users can run:
    PORT=4000 pnpm dev
- README snippet updated to mention the override
- Default stays at 3000 so every existing install, docker-compose file,
  and reverse-proxy rule keeps working

Fixes #96

Co-authored-by: Eric <eric@outsourc-e.com>

README.md

@@ -89,7 +89,7 @@ echo 'HERMES_DASHBOARD_URL=http://127.0.0.1:9119' >> .env
 # If your gateway was started with API_SERVER_KEY (auth enabled), set the same value:
 # echo 'HERMES_API_TOKEN=***' >> .env
 
-pnpm dev                            # http://localhost:3000
+pnpm dev                            # http://localhost:3000 (override with PORT=4000 pnpm dev)
 ```
 
 Requirements on the agent side: